Synthesis, properties and solid lubrication performance of MoAlB-based MBene

Efficient lubrication under harsh conditions is essential for aerospace, automotive, and electrical systems. Novel two-dimensional (2D) materials can serve for this purpose by providing materials with low friction and excellent wear-resistance under these conditions. Therefore, we studied the solid lubrication performance of a novel boridene phase (MoAlB etched into layered 2D Mo2B2 MBene) spray-coated onto stainless-steel substrates. Studies on elemental and phase composition demonstrated the preferential etching of Al over Mo from the parental phase, while infrared spectroscopy confirmed OH and BO groups. The MBene demonstrated adequate colloidal stability, which is essential for the generation of homogeneous solid lubricant coatings. The solid lubrication performance of MBene was tested using ball-on-disk tribometry, revealing a promising reduction in friction and wear by 50%, even under a load of 400 mN (contact pressure of 0.8 GPa). Raman spectroscopy confirmed the formation of a beneficial tribo-layer, comprising both the initial MBene and its oxidation products, which played a cruical role in reducing observed friction and wear. Furthermore, calculated mechanical parameters demonstrated its elastic stability, meeting Born–Huang criteria. Mo2B2's elastic constants fall between other 2D materials such as MXenes, graphene, and MoS2, with surface functionalization impacting its mechanical properties. Altogether, our study provides cutting-edge knowledge about the promising solid lubrication performance of MBenes.